Design of MOF Pores for Enhanced Molecular Recognition in the Crystalline Sponge Method

The crystalline sponge method enables single-crystal X-ray structure analysis of trace organic compounds without crystallization by using porous metal–organic frameworks（MOFs）. This review discusses the design of MOF pores as molecular recognition fields, focusing on APF-series frameworks. In particular, APF-80 employs cooperative coordination and hydrogen-bonding interactions, including structured water networks, to capture diverse guest molecules. Such pore environments allow reliable atomic-resolution structure determination of pharmaceutically relevant and nucleophilic compounds. Rational pore design is shown to be key to expanding the scope and reliability of the crystalline sponge method.